2 #include <linux/slab.h>
3 #include <linux/string.h>
4 #include <linux/compiler.h>
5 #include <linux/export.h>
7 #include <linux/sched.h>
8 #include <linux/security.h>
9 #include <linux/swap.h>
10 #include <linux/swapops.h>
11 #include <linux/mman.h>
12 #include <linux/hugetlb.h>
13 #include <linux/vmalloc.h>
15 #include <asm/sections.h>
16 #include <asm/uaccess.h>
20 static inline int is_kernel_rodata(unsigned long addr)
22 return addr >= (unsigned long)__start_rodata &&
23 addr < (unsigned long)__end_rodata;
27 * kfree_const - conditionally free memory
28 * @x: pointer to the memory
30 * Function calls kfree only if @x is not in .rodata section.
32 void kfree_const(const void *x)
34 if (!is_kernel_rodata((unsigned long)x))
37 EXPORT_SYMBOL(kfree_const);
40 * kstrdup - allocate space for and copy an existing string
41 * @s: the string to duplicate
42 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
44 char *kstrdup(const char *s, gfp_t gfp)
53 buf = kmalloc_track_caller(len, gfp);
58 EXPORT_SYMBOL(kstrdup);
61 * kstrdup_const - conditionally duplicate an existing const string
62 * @s: the string to duplicate
63 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
65 * Function returns source string if it is in .rodata section otherwise it
66 * fallbacks to kstrdup.
67 * Strings allocated by kstrdup_const should be freed by kfree_const.
69 const char *kstrdup_const(const char *s, gfp_t gfp)
71 if (is_kernel_rodata((unsigned long)s))
74 return kstrdup(s, gfp);
76 EXPORT_SYMBOL(kstrdup_const);
79 * kstrndup - allocate space for and copy an existing string
80 * @s: the string to duplicate
81 * @max: read at most @max chars from @s
82 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
84 char *kstrndup(const char *s, size_t max, gfp_t gfp)
92 len = strnlen(s, max);
93 buf = kmalloc_track_caller(len+1, gfp);
100 EXPORT_SYMBOL(kstrndup);
103 * kmemdup - duplicate region of memory
105 * @src: memory region to duplicate
106 * @len: memory region length
107 * @gfp: GFP mask to use
109 void *kmemdup(const void *src, size_t len, gfp_t gfp)
113 p = kmalloc_track_caller(len, gfp);
118 EXPORT_SYMBOL(kmemdup);
121 * memdup_user - duplicate memory region from user space
123 * @src: source address in user space
124 * @len: number of bytes to copy
126 * Returns an ERR_PTR() on failure.
128 void *memdup_user(const void __user *src, size_t len)
133 * Always use GFP_KERNEL, since copy_from_user() can sleep and
134 * cause pagefault, which makes it pointless to use GFP_NOFS
137 p = kmalloc_track_caller(len, GFP_KERNEL);
139 return ERR_PTR(-ENOMEM);
141 if (copy_from_user(p, src, len)) {
143 return ERR_PTR(-EFAULT);
148 EXPORT_SYMBOL(memdup_user);
151 * strndup_user - duplicate an existing string from user space
152 * @s: The string to duplicate
153 * @n: Maximum number of bytes to copy, including the trailing NUL.
155 char *strndup_user(const char __user *s, long n)
160 length = strnlen_user(s, n);
163 return ERR_PTR(-EFAULT);
166 return ERR_PTR(-EINVAL);
168 p = memdup_user(s, length);
173 p[length - 1] = '\0';
177 EXPORT_SYMBOL(strndup_user);
179 void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
180 struct vm_area_struct *prev, struct rb_node *rb_parent)
182 struct vm_area_struct *next;
186 next = prev->vm_next;
191 next = rb_entry(rb_parent,
192 struct vm_area_struct, vm_rb);
201 /* Check if the vma is being used as a stack by this task */
202 static int vm_is_stack_for_task(struct task_struct *t,
203 struct vm_area_struct *vma)
205 return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
209 * Check if the vma is being used as a stack.
210 * If is_group is non-zero, check in the entire thread group or else
211 * just check in the current task. Returns the task_struct of the task
212 * that the vma is stack for. Must be called under rcu_read_lock().
214 struct task_struct *task_of_stack(struct task_struct *task,
215 struct vm_area_struct *vma, bool in_group)
217 if (vm_is_stack_for_task(task, vma))
221 struct task_struct *t;
223 for_each_thread(task, t) {
224 if (vm_is_stack_for_task(t, vma))
232 #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
233 void arch_pick_mmap_layout(struct mm_struct *mm)
235 mm->mmap_base = TASK_UNMAPPED_BASE;
236 mm->get_unmapped_area = arch_get_unmapped_area;
241 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
242 * back to the regular GUP.
243 * If the architecture not support this function, simply return with no
246 int __weak __get_user_pages_fast(unsigned long start,
247 int nr_pages, int write, struct page **pages)
251 EXPORT_SYMBOL_GPL(__get_user_pages_fast);
254 * get_user_pages_fast() - pin user pages in memory
255 * @start: starting user address
256 * @nr_pages: number of pages from start to pin
257 * @write: whether pages will be written to
258 * @pages: array that receives pointers to the pages pinned.
259 * Should be at least nr_pages long.
261 * Returns number of pages pinned. This may be fewer than the number
262 * requested. If nr_pages is 0 or negative, returns 0. If no pages
263 * were pinned, returns -errno.
265 * get_user_pages_fast provides equivalent functionality to get_user_pages,
266 * operating on current and current->mm, with force=0 and vma=NULL. However
267 * unlike get_user_pages, it must be called without mmap_sem held.
269 * get_user_pages_fast may take mmap_sem and page table locks, so no
270 * assumptions can be made about lack of locking. get_user_pages_fast is to be
271 * implemented in a way that is advantageous (vs get_user_pages()) when the
272 * user memory area is already faulted in and present in ptes. However if the
273 * pages have to be faulted in, it may turn out to be slightly slower so
274 * callers need to carefully consider what to use. On many architectures,
275 * get_user_pages_fast simply falls back to get_user_pages.
277 int __weak get_user_pages_fast(unsigned long start,
278 int nr_pages, int write, struct page **pages)
280 struct mm_struct *mm = current->mm;
281 return get_user_pages_unlocked(current, mm, start, nr_pages,
284 EXPORT_SYMBOL_GPL(get_user_pages_fast);
286 unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
287 unsigned long len, unsigned long prot,
288 unsigned long flag, unsigned long pgoff)
291 struct mm_struct *mm = current->mm;
292 unsigned long populate;
294 ret = security_mmap_file(file, prot, flag);
296 down_write(&mm->mmap_sem);
297 ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
299 up_write(&mm->mmap_sem);
301 mm_populate(ret, populate);
306 unsigned long vm_mmap(struct file *file, unsigned long addr,
307 unsigned long len, unsigned long prot,
308 unsigned long flag, unsigned long offset)
310 if (unlikely(offset + PAGE_ALIGN(len) < offset))
312 if (unlikely(offset & ~PAGE_MASK))
315 return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
317 EXPORT_SYMBOL(vm_mmap);
319 void kvfree(const void *addr)
321 if (is_vmalloc_addr(addr))
326 EXPORT_SYMBOL(kvfree);
328 static inline void *__page_rmapping(struct page *page)
330 unsigned long mapping;
332 mapping = (unsigned long)page->mapping;
333 mapping &= ~PAGE_MAPPING_FLAGS;
335 return (void *)mapping;
338 /* Neutral page->mapping pointer to address_space or anon_vma or other */
339 void *page_rmapping(struct page *page)
341 page = compound_head(page);
342 return __page_rmapping(page);
345 struct anon_vma *page_anon_vma(struct page *page)
347 unsigned long mapping;
349 page = compound_head(page);
350 mapping = (unsigned long)page->mapping;
351 if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
353 return __page_rmapping(page);
356 struct address_space *page_mapping(struct page *page)
358 unsigned long mapping;
360 /* This happens if someone calls flush_dcache_page on slab page */
361 if (unlikely(PageSlab(page)))
364 if (unlikely(PageSwapCache(page))) {
367 entry.val = page_private(page);
368 return swap_address_space(entry);
371 mapping = (unsigned long)page->mapping;
372 if (mapping & PAGE_MAPPING_FLAGS)
374 return page->mapping;
377 int overcommit_ratio_handler(struct ctl_table *table, int write,
378 void __user *buffer, size_t *lenp,
383 ret = proc_dointvec(table, write, buffer, lenp, ppos);
384 if (ret == 0 && write)
385 sysctl_overcommit_kbytes = 0;
389 int overcommit_kbytes_handler(struct ctl_table *table, int write,
390 void __user *buffer, size_t *lenp,
395 ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
396 if (ret == 0 && write)
397 sysctl_overcommit_ratio = 0;
402 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
404 unsigned long vm_commit_limit(void)
406 unsigned long allowed;
408 if (sysctl_overcommit_kbytes)
409 allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
411 allowed = ((totalram_pages - hugetlb_total_pages())
412 * sysctl_overcommit_ratio / 100);
413 allowed += total_swap_pages;
419 * get_cmdline() - copy the cmdline value to a buffer.
420 * @task: the task whose cmdline value to copy.
421 * @buffer: the buffer to copy to.
422 * @buflen: the length of the buffer. Larger cmdline values are truncated
424 * Returns the size of the cmdline field copied. Note that the copy does
425 * not guarantee an ending NULL byte.
427 int get_cmdline(struct task_struct *task, char *buffer, int buflen)
431 struct mm_struct *mm = get_task_mm(task);
435 goto out_mm; /* Shh! No looking before we're done */
437 len = mm->arg_end - mm->arg_start;
442 res = access_process_vm(task, mm->arg_start, buffer, len, 0);
445 * If the nul at the end of args has been overwritten, then
446 * assume application is using setproctitle(3).
448 if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
449 len = strnlen(buffer, res);
453 len = mm->env_end - mm->env_start;
454 if (len > buflen - res)
456 res += access_process_vm(task, mm->env_start,
458 res = strnlen(buffer, res);